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Archer Group featured on the cover of Advanced Energy Materials

Tuesday, May 2, 2017

Zhengyuan Tu, Ph.D. candidate in the Archer Research Group describes his work that is featured on the cover of Advanced Energy Materials: "Lithium metal has been regarded as one of the most promising anode materials for high-energy electrochemical energy storage owing to its high capacity, low potential, and compatibility with a number of emerging advanced cathodes. However, unregulated, rough/dendritic lithium electrodeposition during the battery charging is now considered as the main hurdle of the practical lithium metal batteries that can be operated stably and safely for over thousands of cycles required for applications such as transportation. Uncontrolled dendrite formation and proliferation in the closed environment of an electrochemical cell leads to at least two mechanisms of cell failure. First, it increases the surface area of the reactive metal electrode in contact with the electrolyte, which facilitates parasitic reactions between the electrode and electrolyte and continuously depletes the electrolyte and metal electrode. Second, the growing dendrites may become large enough to bridge the gap between the cathode and anode of a battery, producing an internal short-circuit, which can lead to catastrophic cell failure.

Herein, we report a nanostructured electrolyte design that has been theoretically shown recently to be able to suppress the dendrite growth by fundamentally limiting the unfavorable transport. Hybrid electrolytes based on nanoporous - Al2O3 infused with aprotic ether-based liquid are fabricated and studied in detail to understand how confinement of ion transport in nanoporous media influences stability of lithium (Li) metal electrodes. The hybrid electrolytes are found to exhibit liquid-like ionic conductivity and low interfacial impedance at room temperature. Galvanostatic experiments using metallic lithium anodes show that for nano-pores with sizes in the range studied, the hybrid electrolytes enable prolonged, dendrite-free cycling of Li even at a current density of 3 mA cm-2, and the membranes with the smallest nanopore diameters produce the highest efficiency cycling."